By Dr. Mercola
How many meals a day is ideal? There are many answers to this question, but if you want to optimize your lifespan and decrease your risk for developing chronic degenerative diseases, the answer is becoming very clear.
The longstanding conventional answer is that most people need three square meals a day with snacks in between to maintain stable blood sugar and insulin levels.
However, there's compelling evidence suggesting this near-continuous grazing may be partially to blame for the obesity and diabetes epidemic.
The most obvious risk with spreading out your meals to morning, noon, and evening is overeating. Other less obvious risks are biological changes that result in metabolic dysfunction, subsequent weight gain, and diminished health.
Our ancestors did not have access to food 24/7, and from a historical perspective it appears your body was designed for intermittent periods of fasting. In fact, a number of beneficial effects take place when you go for periods of time without eating.
The Case Against Eating Multiple Meals a Day
According to Dr. Valter Longo,1 director of the Longevity Institute at the University of Southern California, where he studies meal timing and calorie restriction, even three meals a day may be too much.
Based on his research, he's convinced the fewer meals you eat, the better you'll fare overall. As reported by Time Magazine:2
"Longo says studies that support a grazing approach tend to be flawed in predictable ways. They often look only at the short-term effects of increasing meal frequency.
While your appetite, metabolism, and blood sugar might at first improve, your system will grow accustomed to your new eating schedule after a month or two. When that happens, your body will start expecting and craving food all day long instead of only around midday or dinnertime."
For the last couple of years, I've suggested limiting meals to a narrow window of six to eight hours — ideally by skipping breakfast, and having lunch be your first meal.
However, we're all different, and some people really struggle without breakfast. More recently, I have refined my views on skipping breakfast.
Eat Breakfast or Dinner, but Not Both...
While I'm still convinced that intermittent fasting is an important strategy for effective weight loss and disease prevention, it likely doesn't matter which meal you skip — breakfast or dinner — as long as you skip one of them.
If you have a physically taxing job, you are likely better off eating a solid breakfast and lunch, and then skipping dinner. The key to remember is to only eat within a window of six to eight consecutive hours each day, and avoiding food for at least three hours before bedtime.
As long as you restrict your eating to this window, you can choose between having breakfast and lunch, or lunch and dinner, but avoid having both breakfast and dinner.
If you chose to eat dinner, it's important to avoid eating for at least three hours before going to bed.
I have recently appreciated that this is another important factor that can help optimize your mitochondrial function and prevent cellular damage from occurring, which I'll review in the next segment.
That said, none of this probably applies to normal weight teens or growing children. They likely need three square meals a day unless they're overweight. For kids and teens, the type of food they eat would be a primary consideration.
Ideally, all of their meals would revolve around eating REAL FOOD — not processed foods, fast food, and sugary snacks. Drinking plenty of pure water and avoiding sugary beverages is another key consideration.
The Benefits of Avoiding Late-Night Eating
If you want to live a long healthy life and avoid chronic degenerative diseases then it's important to have a minimum of three hours after your last food intake before you go to bed.
This is due to the way your body produces energy. Many don't realize that your mitochondria are responsible for "burning" the fuel your body consumes and converting into usable energy.
These tiny bacterial derivatives live inside your cell and are optimized to create energy from the food you eat and the oxygen in the air you breathe. Your cells have between 100 and 100,000 mitochondria.
Your mitochondria create energy by generating electrons that are normally transferred to ATP (adenosine triphosphate). When you don't have insulin resistance this energy transfer works quite nicely, but when you are insulin resistant or you eat excessively, dysfunctions tend to emerge.
If you consume more calories than your body can immediately use, there will be an excess of free electrons, which back up inside your mitochondria.
These electrons are highly reactive and they start to leak out of the electron transport chain in the mitochondria. These excess electrons leak out and wind up prematurely killing the mitochondria, and then wreak further havoc by damaging your cell membranes and contributing to DNA mutations.
There are many knowledgeable experts that believe this type of mitochondrial dysfunction is one of the keys to accelerated aging.
So how can you apply this knowledge? Simple: resolve your insulin resistance as soon as you can, and do not eat for AT LEAST three hours before you go to sleep. Personally I stop eating around 4 PM or even earlier and typically go to sleep around five to six hours later.
Your body will use the least amount of calories when sleeping, so the last thing you need is excess fuel at this time that will generate excessive free radicals that will damage your tissues, accelerate aging, and contribute to chronic disease.
Interestingly, if you have insulin resistance, intermittent fasting is, without a doubt, the most powerful intervention I know of to help you resolve it. This is one of the reasons why I now believe skipping dinner may be an even better strategy than skipping breakfast.
Clearly skipping dinner is more difficult to implement from a social perspective, but it might be a superior biological strategy.
Can Drinking Water Before Meals Help You Lose Weight?
In related news, recent research3 suggests drinking 500 ml (a little more than two eight-ounce glasses) of water half an hour before your meals may help boost weight loss. Obese participants who "pre-loaded" with water before each meal lost an average of nearly three pounds (close to 1.5 kilos) more than the control group over the course of three months.
All participants, including the control group, received a weight management consultation on how to improve their diet and exercise. Those who ate three meals a day and drank water prior to each meal lost an average of nearly 9.5 pounds (4.3 kilos) in three months.
Those who only pre-loaded once a day, or not at all, lost just over 1.75 pounds (0.8 kilos). In all, 27 percent of the treatment group who pre-loaded with water lost more than five percent of their body weight, compared to just five percent of the control group. This makes logical sense, as thirst is often misinterpreted as hunger. Drinking water before settling down to eat will also make you feel fuller, so overall this strategy could result in eating less.
Calorie Restriction Benefits Your Health
Getting back to intermittent fasting, many studies have confirmed the health benefits of calorie restriction, and it seems clear that eating less is part of the equation if you want to live longer. Interestingly, research4 has shown that life-long calorie restriction in mice "significantly changes the overall structure of the gut microbiota" in ways that promote longevity. So one reason why calorie restriction may lengthen lifespan appears to be due to the positive effect it has on gut microbiota.
The increase in longevity is also clearly associated with a decrease in disease states that would cut your life short, and calorie restriction is associated with a number of health improvements, including reduced visceral fat, reduced inflammation, lower blood pressure, and improved insulin sensitivity,5,6 just to name a few. Earlier research has demonstrated that calorie restriction helps extend the lifespan of animals by improving insulin sensitivity and inhibiting the mTOR pathway.
However, few people are keen on the idea of cutting your daily calories by about 25 percent or more for the rest of your life, and the good news is, you don't have to.
Research7,8,9 has shown that intermittent fasting results in many of the same benefits as calorie restriction — even if you don't place any restrictions on the number of calories you consume when you do eat. This was demonstrated in a 2013 review,10 which found a broad range of therapeutic benefits of intermittent fasting, even when total calorie intake per day did not change, or was only slightly reduced. Research included in that review, and other published studies, indicate that intermittent fasting can help:
Limit inflammation, reduce oxidative stress, and cellular damage Improve circulating glucose Reduce blood pressure Improve metabolic efficiency and body composition, including significant reductions in body weight in obese individuals Reduce LDL and total cholesterol levels Prevent or reverse type 2 diabetes, as well as slow its progression Improve immune function,11 and shift stem cells from a dormant state to a state of self-renewal Improve pancreatic function Improve insulin and leptin levels and insulin/leptin sensitivity Reproduce some of the cardiovascular benefits associated with physical exercise Protect against cardiovascular disease Modulate levels of dangerous visceral fat Boost mitochondrial energy efficiency Normalize ghrelin levels, known as "the hunger hormone." Help eliminate sugar cravings as your body adapts to burning fat instead of sugar Promote human growth hormone production (HGH). Fasting can raise HGH by as much as 1,300 percent in women and 2,000 percent in men.12 HGH plays an important part in health, fitness, and slowing the aging process. It's also a fat-burning hormone Lower triglyceride levels and improve other biomarkers of disease Boost production of brain-derived neurotrophic factor (BDNF), stimulating the release of new brain cells and triggering brain chemicals that protect against changes associated with Alzheimer's and Parkinson's disease. (Alternate-day fasting — restricting your meals on fasting days to about 600 calories — can boost BDNF by 50 to 400 percent, depending on the region of the brain.13
Why I Favor Intermittent Fasting Over Calorie Restriction
Intermittent fasting also has a number of added benefits over strict calorie restriction. For starters, it's a lot easier to comply with, and compliance is everything. The calorie restriction route is also extremely dependent on high quality nutrition — you want to sacrifice calories without sacrificing any important micronutrients — and this can be another hurdle for many who are unfamiliar with nutrition and what actually constitutes a healthy diet.
You also want to avoid the counting calories and calorie restriction fallacies. Most people fail to appreciate that there are many intricate biochemical dynamics that occur that are unaccounted for when you just count "calories in and calories out." While animals like rats can achieve a 40 percent increase in longevity through lifelong calorie restriction, such a great effect is not seen in humans, and there are good reasons for that. As pointed out by Fight Aging:14
"There is a good evolutionary explanation for the difference in the calorie restriction response when comparing short-lived and long-lived species: famines are seasonal, and a season is a large fraction of a mouse lifespan but a small fraction of a human life span. Thus only the mouse evolves a relatively large plasticity of life span in response to food scarcity."
In terms of calorie restriction and weight, humans also tend to have an innate resistance to excessive weight loss, even in the face of severe calorie restriction. Dr. Ancel Keys demonstrated this in the mid-1940s when he designed an experiment to investigate the impact of starvation on human beings.
Thirty-six young healthy male volunteers were placed on a 24-week calorie-restricted diet of about 1,600 calories per day. They also had to walk for about 45 minutes a day. But instead of resulting in continuous weight loss, at 24 weeks their weight had stabilized, and no more weight loss could be elicited even when he reduced calorie intake down to 1,000 or less per day.
The drawbacks were clear. The men became obsessed with food to the exclusion of everything else in their life, and when the calorie restriction ended, they all over-reacted. Within a few weeks, they regained all of the lost weight plus about 10 percent more. Other studies have come to similar conclusions. So starvation-type diets may not be ideal for the average person. Your body will tend to shut down various processes in order to survive. For example, by reducing thyroid function, your body will not burn as many calories.
All of this may seem hopelessly contradictory. On the one hand, calorie restriction promotes beneficial biological changes that tend to extend life; on the other, there are built in mechanisms that when triggered by chronic calorie restriction can trigger other health problems. These are complex issues, and any extreme measure is likely to cause more problems than it solves.
The best we can do is come up with some general guidelines that replicate ancestral patterns. In my view, daily intermittent fasting and avoiding eating for a number of hours before bedtime has many advantages over general calorie restriction and other radical diets, while providing many of the same benefits with a minimum of risk.
To Lose Fat You Need to Retrain Your Body to Burn Fat for Fuel
When you consistently eat every few hours and never miss a meal, your body becomes very inefficient at burning fat as a fuel, and this is where the trouble starts. It's important to recognize that, with few exceptions, you cannot burn body fat if you have other fuel available, and if you're supplying your body with carbohydrates every few hours, your body has no need to dive into your fat stores. When you apply intermittent fasting you not only avoid this but also will typically decrease your food costs and increase your health.
Eating fewer meals and timing those meals to occur closer together,15 is one of the most effective strategies I've found to trigger your body to more effectively burn fat for fuel, and normalize your insulin and leptin sensitivity. If you're not insulin resistant, intermittent fasting is not as crucial, but may still be beneficial.
If you're among the minority of Americans who do not struggle with insulin resistance, then my general recommendation is to simply avoid eating at least three hours before bedtime. That automatically allows you to "fast" for at least 11 hours or longer depending on if and when you eat breakfast.
Equally important is the recommendation to EAT REAL FOOD when you do eat, meaning food in the most natural form you can find, ideally whole organic produce, and pasture-raised when it comes to meats and animal products like diary and eggs. To that, I would add avoiding sitting, engaging in non-exercise movement throughout the day, and getting regular exercise. Exercise will not produce significant weight loss without addressing your diet, but when done in combination it can be significantly beneficial.